Rained out? what do you do?
Category: Main
I have a guest blogger today, Presson Sr. who shared some impressive information about the wing tests conducted on Boeing’s new 787 Deamlinder. I added some notes in <>.
And now to his first post:
All our planes, commercial and military, undergo both static (stationary) and fatigue (lifetime) testing before the design is considered satisfactory. The static test gradually increases loading on surfaces, and testing to 1.5 times the "design maximum" is standard, to provide a safety margin. Here in St Louis, we usually refer to that as the design limit loads test. We reserve the term "ultimate load" test for the next level, which is to continue adding loads until the item fails (breaks) – hence, the term "ultimate". It is amazing to see how much the wings bend as it gets to that ends of the testing – without breaking.
The video illustrates how the loading is applied, with hydraulic forces being spread out across the wing length to smoothly load the whole wing, not just the tip or some specific point. <The voiceover gets a bit too rah-rah for the team, but it’s still interesting to watch.>
http://787flighttest.com/boeing-confirms-success-on-ultimate-load-test/
The other major kind of test, fatigue, generates alternating up and down loads (and other kinds* of loading) similar to what the plane will experience in service, and continues the test for days, weeks, and longer, so that the structure gets – literally – a ‘lifetime’ of wear and tear. A month of testing may represent a year of actual service, depending on how many hours per day it is expected to fly. And it’s more complex, since the spectrum of loads used in the test varies to represent takeoffs and landings, climb and descent, cruise, maneuvering, dogfights, and whatever – the so-called "operational mission environment."
Metals do wear out from repeated bending – microscopic discontinuities in material become small cracks after continued service, and small cracks continue grow to become bigger ones. It always surprised me that a crack inspection (no giggles, now) of an airplane in service (done periodically) might result in a note to take another look at some area in between normal inspections. <In other words, small cracks can be ok – don’t think about it when you’re on an airplane.> Crack propagation (how they grow) is a whole field of interest. During the fatigue testing, inspections are done, and this testing also goes "beyond nominal" – I think they do at least 2 lifetimes to be sure. And maybe more.
It can be a great selling point that a plane lasts and lasts (kind of like the bunny). However, we also have to watch out for overdesign. If it lasts too long, we obviously made it too strong, which means too heavy (nasty, nasty), and too expensive (also nasty). The key is continual feedback so we know that we can trust our estimates and our tools – so that when we design for XX performance, the item performs at XX.
* Some are "symmetric", as when both wings bend up, others are not, as during a roll, when one wing bends up and the other down. Obviously, military aircraft tests are a lot wilder. There’s also a drop test, to simulate the vertical impact of an extreme landing (as on a carrier) – which is referred to as a "controlled crash".”
OK I admit it, there are times I stumble on a word for no apparent reason. Although most on-line dictionaries have a pronounce/say-it button, I like the ease of use of this site:
http://www.howjsay.com/index.php?word=dysphemisms&submit=Submit
I had a belly laugh today when I ran across this wonderful link. How many times have you gotten an email or see a post online asking what is xxx? or where do I find that? So what I told you I had a professional photography site named perform photography and neglected to provide a link. Would you post a comment asking where it is? Well, here let me help you find it:
http://lmgtfy.com/?q=performphotography
By the way, you can find my photo site here: http://performphotography.com\
cheers!
Amazing that we are still finding new particles. Meet the antihypertriton..
“Physicists working in the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven Laboratory in the US have detected antimatter nuclei containing strange quarks for the first time. The antihypertriton – consisting of an antiproton, an antineutron and an antilambda particle – is the heaviest antinucleus yet produced and opens up a new realm of strange antinucluei. It could also shed light on a number of problems in astrophysics and cosmology, including the dominance of matter over antimatter in the universe.”
http://physicsworld.com/cws/article/news/41917
I recall being 7 when the movie TRON came out. Dare I say the movie changed my life forever towards IT.
Due to the spectrum reshuffle from switching television to digital broadcasts, a large section of wireless microphones used in houses of worship, clubs, and schools will become illegal to use after Jun 12, 2010. Specifically microphones that use 698MHz through 806Mhz are what will no longer be allowed. Many of the top-of-the-line microphones can be programmed to use frequencies below 698MHz, but these systems typically are $1000 and above in cost. Two manufactures are offering trade-in-rebates to help defer the cost of the change. The biggest problem with this is actually getting the word out to the owners of these systems, since it’s not tracked. So think about your community who may use them and ask if they are aware of the upcoming change. http://arstechnica.com/tech-policy/news/2010/01/time-for-churches-to-come-to-jesus-on-wireless-mic-legality.ars?utm_source=rss&utm_medium=rss&utm_campaign=rss
Back in December 2007, the main nuclear reactor that supplies the majority of the worlds supply of cobalt-60 and almost half of the world’s supply of Tech-99 had to be shut down. This create a shortage of diagnostic and therapeutic nuclear medicine. Apparently the Canadian government saw this possibility and started creation of two new reactors as backups; however, these had to be essentially scraped due to a miscalculation of the power coefficient of reactivity (PCR.) A negative PCR means as the reaction increases, the design of the reactor is such that the reaction will slow down in a negative feedback loop. The only problem was when they started tests, it actually had a positive reaction, meaning it would continue to build unless other safety measures were enabled (inserting rods for example to slow the reaction.) Since the negative PCR was part of the safety spec, it was not allowed to continue.
It’s an interesting read: http://www.newscientist.com/article/mg20527431.400-nuclear-safety-when-positive-is-negative.html?DCMP=OTC-rss&nsref=online-news
Having our first real snow of the year reminded me of something I heard as a kid: when you walk on snow you can gauge the temperature by the pitch of the ‘squeak’ or ‘crunch’ it makes. So of course I decided to do some fact finding, or at least search the web. I found an interesting summary from this blog: http://blog.sciencegeekgirl.com/2008/12/29/why-does-snow-crunch-under-your-feet/ as well as a link to the National Snow and Ice Data Center:http://nsidc.org/snow/faq.html
Apparently at about –10°C there is a change in sound from ‘Crunch’ to a ‘Squeak.’ They suggest there is a thin layer of water on the crystals lubricates above –10°C and does not below –10°C , the squeak sound comes from the crushing of the ice crystals.
I was unable to find anything that indicated the pitch of the squeak changes. On a different note, I noticed last time we visited the beach that my bare feet on the sand causes a similar type of sound.
In any case, next time you go for a walk in the show, listen..
Curious what the view is like atop the the tower Burj Dubai tower? 2,689 feet!! check it out:
Apparently tons of cell phone carriers are having a problem with SMS messages showing a 2016 date instead of 2010, mine included. Interesting thing is 10 in HEX is 16 in decimal, so perhaps the date storing formula as a slight bug? read more here: http://tech.slashdot.org/story/10/01/03/1312209/2016-Bug-Hits-Text-Messages-Payment-Processing
A video to bring a warm smile..
“The enormous Thirty Meter Telescope, with a primary mirror the size of a blue whale, is part of a new generation of super powerful ground-based telescopes. Scheduled for completion in 2018, it will have nine times the collecting power of the Keck telescopes and 12 times the resolution of the Hubble Space Telescope. From its recently selected location atop the volcanic dome of Mauna Kea in Hawaii, the pioneering telescope will provide an extremely detailed look at the universe.”
